The present invention relates to an aerial photogrammetry and an aerial photogrammetric system, using a small type flying vehicle equipped with a camera for photogrammetry on board.
In recent years, with the progress of UAV (Unmanned Air Vehicle), a camera for photogrammetry is installed on UAV and aerial photogrammetry is performed by using the UAV.
In a case where aerial photogrammetry is performed, photographs are taken while flying at an altitude as required at two points so that an object to be measured or a region to be measured is included, relative orientation is performed on images photographed at the two points, and photogrammetry is carried out by performing absolute orientation of the images based on known points (points having a geocentric coordinate already known).
Normally, in aerial photogrammetry, an object and an object to be measured included in an image may be regarded as standstill objects. Therefore, in a case where a flying vehicle is moved for a predetermined time after taking a photograph at a first point and then takes a photograph at a second point, there is no problem in considering that there is no change in the condition of an object or an object to be measured due to the difference in time acquisition between the image acquired at the first point and the image acquired at the second point.
Accordingly, there is no problem even if relative orientation is performed based on the two images which have been photographed at two points respectively, i.e. two images acquired with time difference as necessary. Further, no influence is exerted on relative orientation even when a base line length is increased to improve the accuracy.
In contrast, there are such cases where a detailed image of constructions or a growing condition of agricultural products is observed and measurement is performed by photogrammetry. In particular, in order to observe growing conditions and measure the growth of agricultural products, photographs taken at lower altitude is necessary to observe the conditions of leaves or stems and of measuring height of growth and the like.
When photographs are taken on agricultural products at a low altitude, conditional changes over time such as movings of leaves and stems caused by wind may appear conspicuously on the images taken. Further, there are cases where a moving object such as an automobile may be photographed and included in the images taken to a considerable extent. In cases where there is a difference in the images acquired, the accuracy of the relative orientation is decreased, and the relative orientation may not be accomplished in some cases.
For this reason, it is desirable that there is no time difference or there is almost no time difference between the image acquired at the first point and the image acquired at the second point. However, in a case where the time difference between the image acquired at the first point and the image acquired at the second point is decreased, a moving distance is shortened, the base line length is shortened, and cause the problem of a decrease in the measurement accuracy.